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Friday, June 4, 2010

The potential benefits of vitamin D for various chronic pain conditions continue to generate much interest. As a followup to our earlier reports on this topic, we offer further recommendations for appropriate vitamin D dosing and patient monitoring that should be of interest to practitioners.

In response to our original research reports on “Vitamin D for Chronic Pain” ([available here] and a version of which appeared in the July/August 2008 edition of the journal Practical Pain Management [PDF available here]), Gordon Ko, MD, and Leigh Arseneau, BSc, ND, submitted a letter to the journal editor offering their own “clinical pearls” for vitamin D dosing and monitoring in patients with pain syndromes [Ko and Arseneau 2008]. These practitioners are with the Canadian Centre for Integrative Medicine, Markham, and the University of Toronto, Ontario, Canada. Here are their recommendations for dosing and testing [our notes are in italics]…

As we have noted previously, Ko and Arseneau also point out that during cold weather months when the Sun is weakest it is wise to supplement with vitamin D due to inadequate UVB exposure. Even during other times of the year, most individuals have inadequate UVB exposure due to indoor work or activities and the wearing of clothing or sunscreen when outdoors. The use of UVB tanning beds is an option but this is time-consuming and costly [and there have been renewed concerns about the safety of this approach].

The best supplement to take is vitamin D3 (cholecalciferol). This is the form that also is produced naturally in the skin from UVB exposure; whereas, vitamin D2 or ergocalciferol is produced by irradiating fungi and is less efficient as a precursor to the active vitamin D metabolite calcitriol.

Ko and Arseneau recommend that patients starting on vitamin D3 supplementation should have their vitamin D levels assessed; the correct lab test to order is the 25(OH)D3 blood assay, which reflects the body’s store of vitamin D.

If the patient has a history of kidney stones (calcium oxalate), then it is wise to also measure serum calcium [normal range is approximately 8.5 to 10.2 mg/dL] and the urine calcium/creatinine ratio (the normal range is <1.0 [measurements are in mg/dL; various sources indicate that a ratio >0.26 to 0.33 suggests hypercalciuria]). The authors describe a case in which a patient with prior kidney stones experienced a severe recurrence 4 months after starting a conservative dose of vitamin D. Further examination revealed an elevated serum calcium and parathyroid hormone or PTH level (ie, previously undiagnosed primary hyperparathyroidism).

Ko and Arseneau note that recommended vitamin D3 dosing for healthy adults by various authorities, such as the Canadian Cancer Society, is 2,000 IU/day. Other leading authorities, such as Reinhold Veith, PhD, suggest that oral supplementation is safe for infants at 1,000 IU/day, for children at 2,000 IU/day, and for adults at 4,000 IU/day. More aggressive dosing (up to 10,000 IU/day) may be useful but should be checked with more frequent lab testing (every 3 months).[We had initially suggested 2000+ IU/day of D3 in patients with pain but current research and opinion seems to suggest that is overly conservative in many cases. However, the practice of prescribing megadoses of vitamin D for limited periods of time is controversial and may not be effective, as we recently discussed here]

The authors recommend periodic monitoring of safety and effectiveness by assessing serum 25(OH)D3, serum calcium, and urine calcium/creatinine ratios [however, they do not specify timeframes for monitoring in typical patients; plus it should be noted that they practice in a socialized healthcare system – Canada – where cost may not be an issue]. As a general rule of thumb they propose that the 25(OH)D3 level will increase by 10 ng/mL (25 nmol/L) for each additional 1,000 IU/day of D3 supplementation taken over a 3-month period [which is consistent with the research on this topic]. As the half-life of vitamin D3 is 2 months, they suggest that it may take up to 10 months to reach steady state levels.

Ko and Arseneau usually seek to achieve 25(OH)D3 levels between 40 to 64 ng/mL (100-160 nmol/L). However, they stress that achieving these levels does not translate into significant pain relief for every patient. [Similarly, we noted in our reports that the ideal 25(OH)D3 levels for various pain conditions and individual patients are not determined, so further research in this regard would be helpful.]

As we have noted previously, laboratory testing should be prudently ordered and cautiously interpreted, as there can be factors that skew results; along with that, reference ranges provided by different labs can vary and require some explanation. When initiating an aggressive program of vitamin D supplementation, and depending on patient history, testing may be helpful to rule out pre-existing hypercalcemia or hyperparathyroidism and also establish a baseline 25(OH)D3 level. However, a laboratory report of 25(OH)D3 within an assumed normal range may still be inadequate for an individual patient with chronic pain. Followup testing protocols have not been established and the expense of repeated tests need to be considered. Essentially, until further research can provide validated standards and protocols, each patient might be considered an n-of-1 clinical trial when recommending vitamin D as an adjuvant measure for treating chronic pain. Finally, even if the pain itself is not relieved, other and more subtle benefits may be experienced, such as less need for analgesics, better functionality, improved mood, and others.

DISCLAIMER: Pain Treatment Topics has no involvement or vested interests in the nutritional supplement industry or any other conflicts of interest. The information above is provided for informational purposes only and no representations or claims are made regarding the therapeutic efficacy, appropriateness, or suitability of vitamin D for particular disorders in individual patients.

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